Research And Application Of Roadway Support Technology For Upward Mining Of Protected Seam In Close Distance Coal Seam

When the upper coal seam of the close coal seam is prominent and unstable,the coal is hard and difficult to mine or has no mining value,the upward mining is the most suitable mining method.When the mining method of the mine is upward mining,if the distance between the two coal seams is small,the goaf formed by the mining of the lower coal seam will inevitably have a certain impact on the roadway support of the upper coal seam.At this time,the reasonable selection of roadway support methods and support parameters will affect the normal mining after the mine.Based on the background of No.7 and No.9 coal seams in No.11 mining area of Huaibei Linhuan Coal Mine,this paper studies the support technology of the transport roadway and return air roadway of the overlying No.7 coal seam after the mining of No.9 coal seam（lower protective layer）working face.The distance between No.7 Coal Seam and No.9Coal Seam,which is a close distance coal seam,is an average of 28.5 meters in the lower section of Linhuan Coal Mine.Upward mining is the mining technique.The mining of No.9 Coal Seam currently has an impact on No.7 Coal Seam,the protected layer.The upper coal seam roadway will have the problem of surrounding rock deformation and difficult roadway support.As long as the methods studied in this paper include theoretical analysis,numerical calculation,field application and monitoring analysis,the study achieved the desired effect in roadway support.The research results of this paper are as follows:（1）Considering the influence of No.9 coal seam mining on No.7111 working face,Combined with the influence of the excavation of the lower coal seam on the overlying surrounding rock,the deformation law of the rock stratum is studied from the stress distribution and deformation characteristics of the overlying rock,and the stress distribution of the roadway roof and the two sides.（2）According to the above research results,analyze and determine the height of the two zones by combining the empirical collapse zone and fracture zone formula with the real circumstances of the Linhuan Coal Mine.According to calculations,coal seam 9’s caving zone height is 10.02 m,its fracture zone height is 29.04 m,and its average distance between coal seams 7 and 9 is 28.5 m.The results show that since the height of the fracture zone in Coal Seam 9 is greater than the interval between layers,the overlying rock structure may be damaged to a moderate extent after the coal seam 9 is fully mined,so appropriate support methods must be adopted.（3）In order to study the support effect of 7 coal seam roadway under the influence of goaf,FLAC^3Dis used to simulate and analyze the distribution characteristics of surrounding rock stress and the displacement of roof and floor,two sides and the range of plastic zone of upper coal seam roadway under three support modes after lower coal seam mining.The results show that different support methods are suitable for different sections,which lays a good foundation for the later field application.（4）The optimized support scheme is applied to 7111 coal roadway.The on-site monitoring is used to judge whether the roadway support effect is useful.Based on the monitoring results and practical experience,the relative displacement of the roadway roof and the displacement of the two sides are within the normal and controllable range,and the roof separation amount and bolt force meet the specification requirements,indicating that the support mode and support parameters are designed reasonably.Figure 65 Table 9 References 80...